This invention relates to power distribution systems for electronic circuits and, more particularly, to power distribution systems which employ optical coupling for low power electronic devices.
Prior to the present invention, high density electronic circuits utilized conventional discrete wiring or printed circuit wiring techniques to provide power to the devices of the electronic circuit, whether they be integrated circuits (ICs), hybrids or circuits made up of discrete components. A typical arrangement for supplying electrical power to such circuits is illustrated in FIG. 1 of the drawings. This figure shows an integrated circuit 10 arranged on a printed circuit board 12.
Also shown in the figure are two buses 14 and 16, which typically are made up of metal conductors affixed to the printed circuit board 12, to supply power to devices on the board such as IC 10. Wires or printed circuit connections 18 and 20 are used to connect the appropriate pins of IC 10 to the buses 14 and 16 so as to receive power. These connections 18 and 20 can be made by printed circuit wiring techniques or by discrete wiring. Typically, the printed circuit boards include holes therein in which to mount the pins of the IC with specific ones of the holes connected to the buses 14 and 16. Alternatively sockets are used to accomodate the IC device 10 and the sockets are mounted in the holes of the PC board, with the connections made in the same fashion as if made to the IC device itself.
Typical printed circuits also use a plurality of capacitors 22 connected across the bus lines 14 and 16. These capacitors are used to prevent transient propagation which can cause false triggering of the circuits of the IC devices or, if the devices are analog devices, to prevent corruption of an analog signal.
Many electronic circuits of the type shown in FIG. 1 must be of high density containing a maximum number of components on the printed circuit board. The techniques shown in FIG. 1 detract from the proper space utilization of the board in that the buses that supply power to the devices and the decoupling capacitors consume a lot of space which could accomodate additional ICs.
Another problem associated with power distribution of this type is the excessive current drain which can occur in the event one or more of the ICs connected to the power supply buses becomes shorted. In so called fail-safe systems where redundant circuits are used, failure of an IC due to a short can cause failure of the system even if a redundant IC is provided since current drain due to the short can disable the entire circuit.
Accordingly, it is an object of this invention to provide an improved power distribution system.
It is another object of this invention to provide an improved power distribution system which reduces the amount of space required on a printed circuit board.
It is a further object of this invention to provide a power distribution system which eliminates the requirement for providing decoupling components.
It is yet another object of this invention to provide a power distribution system which is not affected by isolated IC failure due to a shorted IC.